Cannabidiol (CBD) demonstrated short-term neuroprotective effects in the immature brain following hypoxia-ischemia (HI). We examined whether CBD neuroprotection is sustained over a prolonged period. Newborn Wistar rats underwent HI injury (10% oxygen for 120 min after left carotid artery electrocoagulation) and then received vehicle (HV, n = 22) or 1 mg/kg CBD (HC, n = 23). Sham animals were similarly treated (SV, n = 16 and SC, n = 16). The extent of brain damage was determined by magnetic resonance imaging, histological evaluation (neuropathological score, 0-5), magnetic resonance spectroscopy and Western blotting. Several neurobehavioral tests (RotaRod, cylinder rear test[CRT],and novel object recognition[NOR]) were carried out 30 days after HI (P37). CBD modulated brain excitotoxicity, oxidative stress and inflammation seven days after HI. We observed that HI led to long-lasting functional impairment, as observed in all neurobehavioral tests at P37, whereas the results of HC animals were similar to those of sham animals (all p < 0.05 vs. HV). CBD reduced brain infarct volume by 17% (p < 0.05) and lessened the extent of histological damage. No differences were observed between the SV and SC groups in any of the experiments. In conclusion, CBD administration after HI injury to newborn rats led to long-lasting neuroprotection, with the overall effect of promoting greater functional rather than histological recovery. These effects of CBD were not associated with any side effects. These results emphasize the interest in CBD as a neuroprotective agent for neonatal HI.

Delta-9-tetrahydrocannabinol (THC) is the primary psycho-active ingredient in Cannabis spp., the most widely used illicit drug in the United States. THC is an exogenous agonist of the central cannabinoid receptor (CB1), one of the most abundant G-coupled receptors in the mammalian brain. Although CB1 receptors are distributed throughout the brain, they are found at very high levels in the cerebellum. Despite the variety of disturbances associated with acute cannabis intoxication, including altered short-term memory, dissociation of thoughts, motor impairments, and paranoia, among others, a reliable index of cannabinoid system function has in large part eluded scientists. Thus, there is a demand in contemporary clinical neuroscience for methods sensitive to cannabinoid system function, not only for assessing how cannabis use influences human information processing, but also to assess the involvement of the endocannabinoid system (ECS) in clinical disease and evaluate the effects of CB1-based drug therapies. The purpose of the present article, therefore, is to address this current need by integrating two separate literatures. The first literature demonstrates that the ECS mediates synaptic plasticity, specifically, long-term depression (LTD) of parallel fibers at the parallel fiber-Purkinje junction in the cerebellar cortex. The second literature suggests that LTD at this junction is necessary for the acquisition of the primary dependent variable in delay eyeblink conditioning (EBC)--the exhibition of temporally measured conditioned responses. These two literatures are integrated by proposing an updated EBC circuit that incorporates the CB1 receptor and the endogenous cannabinoids. Finally, the implications of the model is discussed in consideration of recent evidence from CB1 knockout mice, human cannabis users, and schizophrenia patients, with the expectation that translational research on the cannabinoid system will be advanced.